This invention pertains to molding devices for molding seamless hollow articles having backdraft or undercut portions on both interior and exterior surfaces. The invention includes a generally hollow one-piece distensible and flexible mold including male and female portions which define a cavity corresponding to the configuration of the molded article. This invention further includes utilizing a vacuum to draw the flexible mold away from the molded article to thereby permit the article to be removed notwithstanding undercut portions formed in the article.
Molding devices generally employing a flexible mold and vacuum means for pulling the flexible mold away from the molded article are shown in the U.S. Pat. No. 3,776,683 issued Dec. 4, 1973 to Putzer et al. The apparatus disclosed therein comprises a distensible flexible mold which may be placed within a vacuum pot such that an annular chamber is formed between the vacuum pot and the mold from which vacuum is drawn to thereby cause the flexible mold to distend, and expand into the chamber and away from the formed article thereby permitting the article to be removed from the mold.